Service key



FIG. 1 is a top, front perspective view of a service key showing my new design;

FIG. 2 is a bottom, rear, right perspective view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a front elevational view thereof, with the rear elevational view being a mirror image thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a right side elevational view thereof; and,

FIG. 7 is a left side elevational view thereof. 

The ornamental design for a service key, as shown and described. 